High energy chemical jet fuel



United States Patent HIGH ENERGY CHEMICAL JET FUEL Robert L. McLaughlin, Woodbury, Lawrence 0. Miller,

vGlassboro, and John W. Schick, Merchantville, N.J., assignors to Socony Mobil Oil Company, Inc., a corporation of New York No Drawing. Filed May 19, 1959, Ser. No. 814,144 2 Claims. (Cl. 52 -5) This invention relates to high energy jet combustion fuel. It is more particularly concerned with agents for increasing the energy content of jet combustion fuels.

Many supersonic aircraft are limited by the volume of fuel that can be carried in the tanks. Thus, a jet fuel with increased energy content per gallon will result in increased operational range or payload. It is highly desirable, therefore, to have jet fuels that have increased volumetric energy content without sacrifice of other conventional characteristics of the jet fuel. Another advantage of fuels of thistype is their excellent thermal stability. A gain in the thermal stability of the fuel allows less weight for insulating or for refrigerating equipment and, therefore, more range or payload. It has been discovered that a combination of certain hydrocarbon compounds has a high number of B.t.u. per gallon together with other properties desirable in a jet combustion fuel.

Accordingly, it is a broad object of this invention to provide a novel high energy fuel. Another object is to provide a jet fuel of high number of B.t.u. per gallon. A specific object is to provide a jet fuel comprising a mixture of specific hydrocarbon compounds. and advantages of this invention will become apparent to those skilled in the art, from the following detailed description.

In general, this invention provides a high energy jet combustion fuel that comprises between about 48 volume percent and about 65 volume percent of isopropylcyclohexane and between about 26 volume percent and about 72 volume percent of 1,1,3-trimethyl-3-cyclohexylhydrindane.

One component of the jet fuels of this invention is 1,1,3-trimethyl-3-cyclohexylhydrindane. This material is readily prepared by hydrogenating, by usual hydrogenation methods, 1,l,3-trimethyl-3-phenylindane.. The latter can be prepared most feasibly by dimerizing alphamethylstyrene to the cyclic dimer. Several methods of making the cyclic dimer are known, but a very efficient method is described ,in copending application Serial No. 803,080, filed March 31, 1959. It will be recognized, however, that the manner of preparing the component contemplated herein is not a limiting factor of this invention, as any method of preparation or any source of the material can be used. a

'lIhe other component of the fuel is isopropylcyclohexane. The particular source of this component is not a limiting factor of this invention. It is a well-known ma- Other objects 2,964,393 Patented Dec. 13, 1960 ice terial that can readily be prepared, for example, by hydrogenating cumene (isopropylbenzene).

The amount of 1,1,3trimethyl-3-cyclohexylhydrindane that is blended with isopropylcyclohexane will depend upon the amount of volumetric energy desired and required. In general, an amount as small as about 26 percent, by volume of the fuel, and as much as about 72 percent, by volume, can be used, the balance being isopropylcyclohexane. Larger amounts will be effective from the standpoint of added volumetric energy, but will tend to increase the viscosity of the fuel beyond desirable limits. In practice, between about 35 percent and about 56 percent, by weight of the finished fuel can be used.

EXAMPLES, 1 AND 2 Two blends of 1,1,3-trimethyl-3-cyclohexylhydrindane and isopropylcyclohexane were prepared. Blend proportions and properties of the blends are also set forth in the table.

Table Composition, Vol. Percent Example 1 Example 2 1,1,3-trimethyl-3-cyclohexylhydrindane. 35 52 Isapropylcyclohexane 65 48 Gravity, API 34. 1 30.6 Freeze Point, F 76 -76 Viscosity, cs.:

18. 475 18, 438 131, 450 134,026 Smoke Point, mm 28 23. 6 Luminosity Number (CRO u no eter) 78 51 In order to obtain the values in the table standard test methods were used, as defined in military specifications. It will be noted that the combination of isopropylcyclohexane and 1,1,3-trimethyl-3-cyclohexylhydrindane gives both high B.t.u./gal. and high B.t.u./lb.

Although the present invention has been described with preferred embodiments, it is to be understood that modifications and variations may be resorted to, without departing from the spirit and scope of this invention, as those skilled in the art will readily understand. Such variations and modifications are considered to be within the purview and scope of the appended claims.

What is claimed is:

1. A high energy jet combustion fuel that consists essentially of between about 26 volume percent and about 72 volume percent of 1,l,3-trimethyl-3-cyclohexylhydrindane and between about 74 volume percent and about 28 volume percent isopropylcyclohexane.

2. A high energy jet combustion fuel that consists essentially of between about 35 volume percent and about 56 volume percent of 1,1,3-trimethyl-3-cyclohexylhydrindane and between about 61 volume percent and about '44 volume percent of isopropylcyclohexane.

, Barnum et al. June 5, 1956 7 

1. A HIGH ENERGY JET COMBUSTION FUEL THAT CONSISTS ESSENTIALLY OF BETWEEN ABOUT 26 VOLUME PERCENT AND ABOUT 72 VOLUME PERCENT OF 1,1,3-TRIMETHYL-3-CYCLOHEXYLHYDRINDANE AND BETWEEN ABOUT 74 VOLUME PERCENT AND ABOUT 28 VOLUME PERCENT ISOPROPYLCYCLOHEXANE. 